LED and halogen lights are original equipment on most cars and trucks sold today, and both types of lighting are widely available in the aftermarket. Until recently LEDs were replacing regular incandescent bulbs in tail lights, parking lights and center high mount stop lights, as well as interior functions like dome lights and instrument lights. Now engineers and designers at the OEM level and in the aftermarket are developing LED lighting for fog lights and headlights, which have traditionally been applications for halogen bulbs. Here is a comparison of these lighting sources:
LED bulbs produce a brighter, cleaner, more attractive light for exterior and interior lighting compared to standard incandescent bulbs, and they're available in various colors.
Halogen bulbs replaced conventional incandescent bulbs in headlights and fog lights because they are brighter and last longer. Today they are used with a reflector or a projector lens. They are available in several degrees of brightness, and color temperatures from 3000K to over 7000K, from yellow to bright white to blue. LED bulbs must be grouped together to provide sufficient intensity and currently they are also being used with reflectors or projector lenses. There are OEM LED headlights that currently provide light at 5500 on the Kelvin scale, which is approximately the same as daylight. It remains to be seen whether the light quality of halogen headlight and fog light bulbs can be improved in response to competition from LEDs, but LED headlights have already matched the light quality of halogen bulbs and are sure to improve going forward.
LED bulbs have significant advantages over halogen bulbs in lifespan and cost of operation. A typical LED will operate for 50,000-75,000 hours, more than the life of the vehicle to which it is attached and far longer than the typical 1000-2000 hour lifespan of a halogen bulb. An LED will also consume up to 90% less power than an incandescent bulb, and since less power is needed, the generator doesn't have to work as hard, reducing the load on the engine and saving fuel. However, the operational savings must be balanced with higher initial cost. Halogen bulbs are a mature technology and less expensive to purchase. While LED lights have been used for many other applications on the automobile, their use for headlights and fog lights is new and likely to be more expensive. Also, while power to halogen bulbs can be supplied directly from the vehicle's electrical system, LEDs may require drivers to ensure a constant current supply.
One aspect particularly beneficial to cars and trucks is how fast LEDs reach their full intensity. LEDS rise to full intensity approximately 200 milliseconds (0.2 seconds) faster than incandescent bulbs, or about 10 times faster. This may not sound like a lot, but it may be all the time that's needed for the driver behind you to see your brake lights and react to avoid a potential accident.
Halogen bulbs operate at very high temperatures, so the lighting fixtures they're used in must be carefully designed with this in mind. The proper materials must be used and there must be adequate clearance around the bulb. Also, the bulb must not be touched with bare hands, as the oils from the skin can burn when the bulb is on and create hot spots, significantly weakening the bulb to the point it fails. In contrast, LED bulbs produce almost no infrared radiation. This allows vehicle engineers to position LEDs in closer proximity to other components and make more efficient use of available space.
Anyone that drives on today's pothole-strewn roads knows that our cars and trucks are constantly subjected to shocks and vibrations. These forces can cause delicate incandescent bulbs to fail, but LEDs are impervious to such conditions.
The compact size of LEDs enables designers to be creative with design and economical with space. LEDs can be organized in patterns that give a brand a distinctive "signature" that is recognizable by other drivers. They can also be combined to make lights more compact and aerodynamic.